﻿<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>:after选择器</title>
    <style type="text/css">
        strong:after{content:url(images/1.png);}
    </style>
</head>
<body>
    <strong>天文学</strong>
</body>
</html>
    
    
    
    
    
    
    
    
    